The construction of a main body of a conventional ink jet printer will be described. For conventional printers, a divided chassis construction using a metalwork material has been adopted. On chassis members in the divided chassis construction, constituent members relating to recording are positioned and held.
The construction of a printer disclosed in U.S. Patent Publication No. 2006/0024118 will be described by way of example with reference to FIG. 23. A multiple feed unit section (not shown) 10 having a plurality of feed sections and a both-side transport section is fixed in a state of being interposed between a right chassis 112 and a left chassis 113. The right chassis 112 and the left chassis 113 are formed of a metalwork material or the like having a certain strength. A main chassis 11 formed of a metalwork material is provided on the front sides of the right chassis 112 and the left chassis 113. A transport section unit including a transport roller, a pinch roller and a platen and a printing section unit including a carriage and a printing head, which units are not shown in the figure, are fixed on the main chassis 11. The main chassis 11 has side plate portions 11A and 11B constructed by bending a sheet metal. A stay member (platen chassis) 114 and a stay member (front chassis) 115 are connected between the side plate portions 11A and 11B to improve the rigidity.
With respect to printers such as personal printers, there is an increasing demand for further reducing the size and cost of the apparatus. Also, with the improvement in image quality in photographic printing, a demand for improving the accuracy in recording performance is increasing. In some cases, under circumstances where such demands are increasing, problems described below have arisen with the above-described conventional example.
On the left side plate portion 11B of the main chassis 11, a carriage shaft on which the carriage not shown in the figure is held and members of a transport system such as a transport roller and a platen are positioned and held. Since the component parts in the printing section system and the component parts in the transport system are positioned on the same left side plate portion 11B, the component parts can be mutually positioned with good accuracy. However, since positioning portions are formed on one bent portion, there is a need to form a sheet metal bending position in correspondence with the position of the component part requiring the largest of the widths of the mutual positions necessary in the widthwise direction. In some cases, therefore, the component parts in the printing section system and the component parts in the transport system cannot be disposed at the optimum positions in the widthwise direction, and it is difficult to pursue a further reduction in size in the widthwise direction and a reduction in cost in component part cost-cutting by reducing the width.
Also, in some cases, the transport roller and a discharge roller are adjusted in length to the carriage shaft and therefore have such an increased length that the influence of a deterioration in transport accuracy due to flexures of the shaft of the rollers is large. On the right side plate portions 11A (two places) of the main chassis 11, the carriage shaft and the members in the transport system including the transport roller and the platen, not shown in the figure, are positioned and held on separate side plates. Therefore errors in position accuracy of the recording system component parts and the transport system component parts are increased due to an error in sheet metal bending accuracy, resulting in a deterioration in recording accuracy and, in some cases, failure to perform construction with high-accuracy positioning.
On the right chassis 112 and the left chassis 113 on which the multiple feed unit section 10 having the plurality of feed sections and the both-side transport section is positioned, a feed roller and a both-side transport roller, not shown in the figure, and other components are positioned and held for the sheet maximum width. Therefore the right chassis 112 and the left chassis 113 are constructed so as to be different in position in the widthwise direction from the side plate portion 11B. Consequently, it is necessary to form the left chassis 113 and the side plate portion 11B as separate component parts. In some cases, an increase in cost and a reduction in space efficiency result from the increase in number of component parts. As a solution to this problem, forming the left chassis 113 and the left side plate portion 11B from an integral sheet metal is conceivable. In forming the left chassis 113 and the left side plate portion 11B in such a way, however, bending is required in two places because of the difference in position in the widthwise direction and a problem newly arises that the position accuracy of the component parts is reduced by bending.
Since sheet metals are used for the purpose of increasing the rigidity, rotatable or movable parts including transport system component parts such as the transport roller, pinch rollers urged against transport system component parts to produce transport force, a movable sheet guide flapper and the like cannot be directly held by the sheet metals. That is, the rotatable or movable parts are fixed on sheet metal chassis by means of slide members such as bearings formed of a resin material. An increase in the number of component parts results from this and a problem may arise that an increase in cost and a reduction in space efficiency make impossible the pursuit of a further reduction in size. Moreover, in some cases, forming all the chassis portions constituting the main body frame from sheet metals inhibits a reduction in cost and a reduction in weight of the main body.